On a Boundary Model in Problems of the Gas Flow around Solids

This paper studies the development of a multiscale approach to calculate the gas flows near solid surfaces taking into account microscopic effects. In this line of research, the problem of setting boundary conditions on the surface of a solid body is considered, taking into account the effects preliminarily calculated at the atomic-molecular level. The main aim of this paper is to formulate macroscopic boundary equations that take into account the processes on the surface of a solid body around which there is a flow of gas. The macroscopic model is based on a system of quasi-gasdynamic (QGD) equations in the volume and the thermal conductivity equation in the near-surface layer of the streamlined body. The system is supplemented with real gas state equations and dependencies of the kinetic coefficients of the QGD equations on temperature and pressure, obtained on the basis of molecular dynamics calculations. To test the proposed boundary equations, the problem of the gas flow around a blunt body is considered. Dry air is selected as the gas. Nickel is chosen as the body coating. Calculations are carried out for two values of the inlet velocity. They confirm the qualitative correctness of the developed boundary model and the entire modeling technology.